The proportion of certain HRD alterations was higher in our cohort than in previously reported mCRPC populations [68, 69], e.g. BRCA1 and ATM. We speculate that this may be attributed to having selected patients with ctDNA% of 3 or more, as we, and others, have previously shown that prostate cancer patients with germline DNA repair gene alterations have poorer outcomes (in particular BRCA2 and ATM germline variants) [70, 71], and this may also be the case for somatic alterations [72, 73]. This evidence concerns the gene BRCA1 and prostate cancer.